Electrical toothbrush

ABSTRACT

An electric toothbrush with a grip section, a brush head which is mounted for movement relative to the grip section and a drive mechanism for driving the brush head in an oscillatory and/or orbital motion. The brush head includes a cleaning fork having legs lined with a piece of plush or velvet on their insides.

TECHNICAL FIELD

This invention relates to an electric toothbrush with a grip section, abrush head which is mounted for movement relative to the grip section,and a drive mechanism for driving the brush head in an oscillatoryand/or orbital motion.

BACKGROUND

In order to accelerate the dental cleaning process and to make it morethorough, it has already been proposed to form the toothbrush head in amanner which enables a plurality of tooth surfaces to be worked onsimultaneously. For example, it has thus been proposed to arrange threebristle sets at an angle of approximately 45° to each other on the brushhead, and to place them in gripper-like fashion on the tooth to becleaned, so that the tooth can be cleaned simultaneously from threesides. Cleaning three surfaces simultaneously shortens the time requiredfor cleaning, and additionally offers the advantage that individualtooth surfaces are less easy to forget during cleaning.

However, the arrangement of a plurality of bristle sets for the purposeof cleaning a plurality of tooth surfaces makes the brush headdisproportionately large. In order to give the bristles a certainsoftness, they must have a corresponding length when using the currentlytypical filaments. As a result, the cleaning head becomes very large.The size of such brush heads is perceived to be uncomfortable in themouth, resulting in the brush often not being pushed all the way to therearmost molars. Furthermore, the teeth are hugged only to a limitedextent. As a result, particularly the round canine teeth areas and theincisors, which have varying occlusal and coronal thicknesses, are notcleaned optimally.

German patent DE 693 24 373 T2 discloses a toothbrush, in which thebrush head has a part that is shaped to conform to the contour of amolar, and which has on its U-shaped inside surface with a set ofbristles, which work on the molar from three sides. However, this shapedpart which forms the brush head is very bulky and suffers from thedisadvantages outlined above.

SUMMARY

One aspect of the present invention features an electric toothbrush witha grip, a brush head which is mounted for movement relative to the gripsection and a drive mechanism for driving the brush head in anoscillatory and/or orbital motion. The brush head has a cleaningelement, for example a cleaning fork, the legs of which have a piece ofplush or velvet on their insides. No array of bristle sets on aplurality of sides is provided. Instead, a cleaning element is providedwhich is lined with a thin, non bulky piece of plush or velvet, allowingthe toothbrush head to have a compact design despite hugging therespective tooth on a plurality of sides. In conjunction with the plushor velvet lining, the oscillatory and/or orbital driving motion of thebrush head results in excellent interproximal cleaning. An individualtooth can be cleaned simultaneously from all three sides, i.e., from thebuccal, lingual, and occlusal sides, resulting in a more thorough andfaster cleaning. By using the piece of plush or velvet instead ofbristle sets, a compact brush head, which is perceived as beingcomfortable in the mouth during usage, can be achieved.

The piece of plush or velvet can be a piece of fabric with a pile, forexample, and both the piece of fabric and the pile can be made ofpolyamide.

Although a variety of velvet or plush pieces can be used, in aneffective example the pile has a depth of approximately 2-8 mm,preferably approximately 3-6 mm.

In this arrangement, the depth of the pile may vary across the cleaningelement. The pile of the piece of plush or velvet may have a greaterdepth at the free end of the legs of the cleaning fork, than at a rootor foot section of the legs.

The pieces of plush or velvet have pile yarn, which has a thicknessranging from 0.05-0.2 mm, for example about 0.1 mm. The thickness of thepile yarn may also vary across the cleaning element. For example, insome embodiments, the pile yarn at the free ends of the legs is thinnerthan in the root or foot sections of the legs.

In some embodiments, only the legs of the cleaning fork are equippedwith one piece of plush or velvet each. In some other embodiments, across bar which connects the legs of the cleaning fork may also beprovided with a piece of plush or velvet on the inside, resulting in aU-shaped plush or velvet lining on the inside contour of the cleaningfork.

In order to be able to adapt the cleaning fork to a variety of toothcontours, and to clean teeth of varied widths with uniform efficiency,in some embodiments the cleaning fork is formed in such a way that thelegs are capable of springing relative to each other. The legs of thecleaning fork may be sprung themselves. Alternatively, they may beformed in a manner of a joint in their foot or root area and be actedupon by a spring which biases the legs towards each other. The legs canbe designed to be sprung in their entirety, as a result of which betteradaptation to the tooth contour is achieved. The distance between thelegs can be chosen so that the cleaning fork expands slightly whenplaced on a tooth, resulting in the legs being spring-biased against theflanks of the teeth.

The legs of the cleaning fork may enclose an angle of 15° to 45° betweeneach other. The free ends of the legs may be expanded in a bell-shapedconfiguration.

In some embodiments, the cleaning fork has two legs, i.e., it may beformed as a simple, U-shaped fork. In another embodiment, the cleaningfork has four legs which extend in pairs on opposite sides. With the aidof such a double fork, both the mandibular teeth and the maxillary teethcan be cleaned simultaneously. If appropriate, the legs on the one sidemay be at a smaller relative distance than the legs on the other side,as a result of which the different widths of fork can be used fordifferent tooth areas.

In some embodiments in order to be able to place the brush head on a rowof teeth without corresponding accurate alignment of the grip section ofthe toothbrush, in a further development of the invention the brush headis mounted on a brush head carrier for rotation about a transverse axiswhich extends substantially perpendicular to the longitudinal axis ofthe toothbrush, such that the brush head is not driven in relation tothis transverse axis. At the toothbrush end facing away from the gripsection, the transverse axis extends parallel to the direction in whichthe cleaning fork is placed on the teeth. It can extend through theplane of symmetry of the cleaning fork. Preferably, the possible angleof rotation is sufficiently large to allow the cleaning fork which hasbeen placed on the teeth to be moved from the left-hand side of the jawto the right-hand side of the jaw without lifting the cleaning fork fromthe teeth.

The rotary mounting of the brush head about the non-driven transverseaxis is preferably of the retarding type so that, although the brushhead can be rotated arbitrarily, it comes to a standstill in therespective position in the absence of the action of forces.

The drive mechanism may be constructed differently in terms of thegenerated drive motions of the brush head. According to another aspectof the invention, the drive mechanism has a drive axis which is parallelto the longitudinal axis of the toothbrush, and about which the brushhead is adapted to be driven in a preferably conically orbital motion.Particularly good cleaning results can be achieved with the plush orvelvet lined cleaning element by providing for a nutating drive motionof the brush head about the longitudinal axis of the toothbrush. Acleaning motion in three directions is accomplished with the aid of asuitable nutating drive, namely along the tooth height, across the widthof the tooth, and perpendicular to the primary tooth surface, or in anydesired combination of these directions, and as a result dirt can beremoved thoroughly.

In order to drive the brush head conically in an orbital path about thelongitudinal axis of the toothbrush, the brush head may be seated upon abrush head carrier, which is constructed as a driving rocker. The brushhead carrier can be mounted in the fashion of a ball-and-socket joint,at a pivot point between the brush head and a motor arranged in the gripsection, and having a drive coupling element at its end remote from thebrush head. The design of the brush head carrier as a spatial rockerwhich is driven in a double-conical orbital motion achieves a multi-axiscleaning motion using a simple construction. The brush head carrier canbe mounted non-rotatably about its longitudinal axis, and as a result itdoes not rotate about itself during the nutating motion about thelongitudinal axis of the toothbrush. The brush head carrier may befastened at the pivot point to an elastic bearing element, which allowsan at least limited motion of the brush head carrier in the manner of aball-and-socket joint.

Preferably, the drive coupling element of the brush head carrier is ofthe releasable type, in which the brush head carrier is releasablysecured to a brush shank, which connects the brush head to the gripsection, so that the brush head carrier is exchangeable, i.e., it isdetachable from the remainder of the toothbrush and replaceable in themanner of a refill.

A releasable connection can also be provided between the brush head andthe brush head carrier, allowing the brush head to be exchanged, i.e.,to be detached from the brush head carrier and replaced with a refill.

A driving rocker can be provided in order to drive the brush headcarrier. The driving rocker is mounted in the manner of aball-and-socket joint at a pivot point on the grip section and is drivenin a spatially orbital motion by the motor which is arranged in the gripsection. For this purpose, an eccentric member may be seated on themotor shaft. The eccentric member is in engagement with the motor-sideend of the driving rocker. The brush head-side end of the driving rockeris engageable with the brush head carrier, which is also formed as adriving rocker, so that the conically orbital motion of the drivingrocker is translated into a corresponding motion of the brush headcarrier. The driving rocker has a releasable connection member forreleasable connection to the brush head carrier.

In some embodiments, the driving rocker is non-rotationally mountedabout its longitudinal axis, being fastened to an elastic bearingelement at the pivot point on the grip section side. In this way, thegrip section can be hermetically sealed in a simple manner, as there isno relative movement between the bearing element and the driving rocker.

As an alternative to the driving rocker on the grip section side, adrive shaft, which projects from the grip section and has a drive memberwhich rotates eccentrically, can be provided for driving the brush headcarrier. The drive member is engageable with the end of the brush headcarrier, which is on the grip section side. In this case, a radial shaftseal is provided at the point at which the drive shaft passes throughthe forward end of the grip section.

The connection between the drive member on the grip section side, i.e.,the driving rocker or the rotary drive shaft with eccentric member, andthe brush head carrier may be designed to substantially have zero play.As a consequence, the drive motion of the drive member on the gripsection side is translated into a corresponding orbital drive motion ofthe brush head carrier, which is formed as a rocker.

It may however also be desirable to translate only part of the drivemotion of the drive member on the grip section side into a correspondingdrive motion of the brush head carrier. To do this, the connectionbetween the driving rocker on the grip section side, or the rotatingeccentric member on the grip section side and the brush head carrier maydisplay at least limited play in at least one direction transverse tothe longitudinal direction of the toothbrush. For example, the drivingrocker on the grip section side may sit in an elliptic or oval sleevewhich is secured to the brush head carrier. The brush head carrier mayalso have a slotted recess at its end close to the grip section. Thedriving rocker of the grip section is seated in the slotted recess. As aconsequence of this arrangement, the amplitude of the drive motion ofthe drive member on the grip section side is transmitted in full in onedirection, but in the direction perpendicular thereto, it is transmittedonly in part, or not at all.

In some cases, the drive mechanism includes an adjusting device foradjustment of the stroke of the brush head motion. The adjusting deviceallows adjustment of the lever ratios of the driving rocker on the gripsection side and/or the brush head carrier which is also constructed asa driving rocker. For example, the pivot point, at which the brush headcarrier is mounted in the manner of a ball-and-socket joint, may bedisplaced in the longitudinal direction of the toothbrush. It is equallyconceivable to displace the corresponding pivot point of the drivingrocker on the grip section side. As an alternative or as an addition,the point of application of the eccentric member seated on the motorshaft may be changed at the driving rocker on the grip section side. Theadjustable stroke of the nutating motion of the brush head enables themotion of the brush head to be adjusted from gentle, i.e., shortmotions, to strong, i.e., large motions, according to the preferences ofthe user.

The brush head carrier does not necessarily have to be driven in aconically orbital motion about the longitudinal axis of the toothbrush.In some embodiments, the drive mechanism can have a drive axis which isparallel to the longitudinal axis of the toothbrush and about which thebrush head is driven in an oscillatory rotational motion. As analternative or as an addition, the drive mechanism may have a drive axiswhich is parallel to the longitudinal axis of the toothbrush, and alongwhich the brush head is adapted to be driven in a translatoryoscillating motion, i.e., the brush head is moved back and forth. As analternative or as an addition, the drive mechanism may also have afurther drive axis which extends in a direction transverse to thelongitudinal axis of the toothbrush and about which the brush head isdriven in an oscillatory rotational motion. This transverse axis mayextend parallel to a plane of symmetry of the cleaning element, and maypreferably be arranged substantially at the end of the grip section onthe brush head side. Accordingly, the brush head with the plush orvelvet lined cleaning element is swiveled to and fro to the right and tothe left in an oscillating motion. As an alternative or as an addition,a drive axis may also be provided which extends perpendicular to theplane of symmetry of the cleaning element, which is also preferablyarranged at the end of the grip section on the brush head side.Accordingly, the brush head is rocked up and down at the tooth flanks,as a result of which any dirt which is located in the interproximalspaces can be removed.

The piece of velvet or plush may be fastened to the cleaning element ina variety of ways. The piece of velvet or plush may be secured to thecleaning element by forming a firm bond between the materials involved.In particular, the respective piece of velvet or plush may be adhesivelybonded to the inside of the cleaning fork, for example, by means of asilicone adhesive, or it may be secured by hot-sealing.

As an alternative or as an addition, the piece of velvet or plush may befastened by positive engagement, for example, the respective piece ofvelvet or plush may be clamped by its edges under a clamping bar of thecleaning element, or of a plush supporting structure attached to it.

If appropriate, the piece of velvet or plush may be secured by just itsedges to the free ends of the legs of the cleaning fork. Additionally,the piece of velvet or plush can be secured to the bottom of the crossbar connecting the legs, so that the piece of velvet or plush is onlytensioned in a V-shaped configuration, such that it does not make fullsurface contact with the inside contour of the legs of the cleaningfork. Only when the cleaning fork is pushed onto the tooth being cleaneddoes the velvet or plush strip make full surface contact with the insidecontour of the legs and/or the outside contour of the tooth.

Further objects, advantages, features, and application possibilities areset out in the subsequent description of preferred embodiments withreference to the accompanying drawing.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, perspective view of an electric toothbrush havinga velvet- or plush-lined cleaning fork capable of being driven by anutating drive;

FIG. 2 is a schematic, perspective view of an alternative, U-shapedcleaning fork and of a tooth onto which the cleaning fork can be placed,the cleaning fork being designed for the toothbrush of FIG. 1;

FIGS. 3A-3C are schematic views of a variety of embodiments of aneccentric member which is seated on the motor shaft for the nutatingdrive of the toothbrush of FIG. 1;

FIG. 4 is a schematic, perspective view of an electric toothbrushsimilar to FIG. 1, wherein the nutating drive has a drive shaft with aneccentric member instead of a driving rocker which rotates spatially;

FIG. 5 is a schematic, perspective view of an embodiment of the electrictoothbrush, wherein a bell-shaped cleaning fork is mounted on a brushhead carrier for rotation about a transverse axis, the brush headcarrier being capable of being driven in nutating fashion;

FIG. 6 is a longitudinal section of a schematic partial view of anotherembodiment of the electric toothbrush;

FIG. 7 is a longitudinal sectional view of the electric toothbrush ofFIG. 6 taken along the line A-A of FIG. 6;

FIG. 8 is a cross-section through the brush shank of the toothbrush ofFIG. 6 taken along the line B-B of FIG. 6;

FIG. 9 is a cross-section through the brush head of the toothbrush ofFIG. 6 taken along the line C-C of FIG. 6;

FIG. 10 is a schematic representation of the cleaning fork of thetoothbrush of the preceding FIGS. 6 to 9 when it is placed on anincisor;

FIG. 11 is a schematic representation of the cleaning fork of thetoothbrush of the preceding FIGS. 6 to 9 when it is placed on a molar;

FIG. 12 is a partial schematic plan view of a brush head for atoothbrush according to FIG. 6 which carries an additional lateralweight;

FIG. 13 is a representation showing the function of the toothbrush ofthe preceding FIGS. 6 to 9 placed on a row of teeth, which highlightsthe capability of the cleaning fork to rotate about a transverse axis;

FIG. 14 is a longitudinal section of a schematic partial view of anelectric toothbrush according to another embodiment, wherein thetoothbrush has a double fork with legs pointing upward and downward;

FIG. 15 is a longitudinal sectional view of the toothbrush of FIG. 14taken along the line E-E of FIG. 14;

FIG. 16 is a cross-section through the brush shank of the toothbrush ofFIG. 14 taken along the line F-F of FIG. 14;

FIG. 17 is a cross-section through the brush shank of the toothbrush ofFIG. 14 taken along the line G-G of FIG. 14;

FIG. 18 is a cross-section through the brush head of the toothbrush ofFIGS. 14 and 15 taken along the line H-H of FIG. 14;

FIG. 19 is a longitudinal section of a schematic partial view of anelectric toothbrush according to another embodiment;

FIG. 20 is a longitudinal section of a schematic partial view of anelectric toothbrush according to another embodiment;

FIGS. 21A and 21B illustrate a schematic representation of a cleaningfork having a piece of plush fastened to the free ends of the legs andto the base of the cleaning fork, wherein FIG. 21A shows the cleaningfork prior to being placed on a tooth for cleaning and FIG. 21B showsthe cleaning fork following its placement on the tooth;

FIGS. 22A and 22B illustrate a die for forming a piece of plush orvelvet for a cleaning fork of a toothbrush from the preceding Figures,wherein FIG. 22A shows the piece of plush or velvet prior to forming andFIG. 22B shows the piece of plush or velvet subsequent to its forming inthe die; and

FIG. 23 is a schematic representation of a piece of plush or velvetwhich is secured to the legs of a cleaning fork by making positiveengagement therewith.

DETAILED DESCRIPTION

The toothbrush shown in FIG. 1 has a grip section 1 and a brush head 2,which is connected to the grip section 1 by means of a brush tube 3. Thebrush head 2 is mounted for movement relative to the brush tube 3 and isadapted to be driven by a drive mechanism 5 in a manner which will bedescribed in more detail below.

A housing 4 of the grip section 1 accommodates a motor 6, which in theshown embodiment is supplied with energy from batteries 7. The batteries7 are arranged in the grip section 1 behind the motor 6 and may be inthe form of primary or secondary batteries. If secondary batteries areused they can be charged inductively or via contacts by means of acharging device not illustrated here in greater detail.

The motor 6 comprises a motor shaft 9 which extends substantiallyparallel to the longitudinal axis 8 of the toothbrush and has adisc-shaped eccentric member 10 seated thereon. The eccentric member 10is pivotally connected to a driving rocker 11 in order to drive it in aconically orbital motion. The driving rocker 11 penetrates through theforward end of the housing of the grip section 1, so that it extendsfrom within the grip section 1 through the forward end and into thebrush tube 3. It is mounted in the fashion of a ball-and-socket joint onthe forward end wall 12 of the grip section housing 4. In thisarrangement, the ball-and-socket-joint-like pivot point 13 is formed bymeans of a rubber-like, plug-type sealing element 14, in which thedriving rocker 11 is inserted. The sealing element 14 sits in thepassage opening 15 in the forward end wall 12 of the grip sectionhousing 4, in order to seal the point at which the driving rocker 11passes through the grip section housing 4.

The driving rocker 11 sits in a non-rotating relationship in the sealingelement 14 so that it does not rotate about itself when it is driven bythe eccentric member 10 in a conically orbital motion about thelongitudinal axis of the toothbrush. This significantly facilitatessealing.

With its end remote from the motor 6, the driving rocker 11 is pivotallyconnected via a coupling element 16 to a brush head carrier 17, as aresult of which the drive motion of the driving rocker 11 is transferredonto the brush head carrier 17. In the embodiment shown in the drawing,the coupling element 16 is a coupling sleeve receiving the forward endof the driving rocker 11, the coupling sleeve being rigidly fastened tothe end of the brush head carrier 17.

The brush head carrier 17 is mounted via a ball-and-socket joint 18 on asliding member 19 which is slidably mounted in longitudinal direction ofthe toothbrush on the brush tube 3 and is adapted to be locked in adesired position by means of notches 20, for example. As shown in FIG.1, the sliding member 19 and the brush head carrier 17 are arranged inthe interior of the hollow brush tube 3. Via an inserted profile ring21, the brush tube 3 is releasably secured to a brush tube mounting 22on the forward end wall 12 of the grip section 1.

The brush head carrier 17 emerges at the forward end of the brush tube 3on the side remote from the grip section 1 and carries the brush head 2at its forward end. In the embodiment shown in the drawing, the brushhead 2 comprises a cleaning fork 23 which is secured by means of areleasable connection 24 to the brush head carrier 17. In the embodimentshown, the cleaning fork 23 is constructed as a simple U-shaped forkhaving two legs 25 which are preferably sprung in a manner which allowsthem to spring in a direction away from each other. In the embodimentshown, the two legs 25 are biased against each other by means of apressure spring 26. Where applicable, the legs 25 may have a joint intheir connecting area. In some embodiments, they are injection moldedfrom plastic, so that the legs 25 possess sufficient elasticity to allowthem to spring to an open and a closed position. The biasing of the legs25 causes the legs 25 to engage the outer sides of a tooth in thedesired fashion.

As shown in FIG. 1, contoured cleaning element holders 27 are attachedto the free ends of the legs 24 on the insides thereof. The cleaningelement holders are provided with one cleaning element 28 each on theinside, in the form of a piece of plush or velvet 29. The cleaningelement holders 27 are releasably secured by means of releasableconnecting elements 30, for example locking clips, to the legs 25 of thecleaning fork 23. As shown in FIG. 1, the cleaning element holders 27and the cleaning elements 28 attached to them extend in a directionsubstantially transverse to the longitudinal direction of the brush headcarrier 17. They widen in a bell-shaped configuration towards one end,and as a result they can be pushed on to the tooth with greater ease. Insome embodiments, the cleaning elements 28 are rotatable relative to thebrush head carrier 17 about a transverse axis which extends parallel tothe plane of symmetry of the cleaning fork 23, so that the cleaning fork23 can slide from the left-hand side of the jaw to the right-hand sideof the jaw while sitting on the teeth, and without it being necessary toturn over the grip section. The cleaning fork 23 is therefore capable ofrotating about the Z-axis shown in FIG. 2 which is perpendicular to theprimary surface of the tooth. The rotatability is preferably of thedecelerated or retarding type so that the brush head comes to astandstill in the respective position in the absence of any forcesacting on it.

Due to the rotation of the motor shaft 9, the eccentric member 10rotates, causing the pivot point 31 of the driving rocker 11 at theeccentric member 10 to describe a circular path, and the driving rocker11 to describe a conical or double-conical orbital path. As the drivingrocker 11 performs no rotation about its own axis, it is possible tohermetically seal the grip section in a simple manner through thebearing and sealing element 14.

The opposite end of the driving rocker 11, which is engaged with thecoupling element 16, performs a corresponding motion along a circularpath, with the diameters of the circular paths being proportional to thelever lengths l¹ and l₂ (see FIG. 1). The opening angle of the tworesulting cones of the orbital motion is α₁ in each case (see FIG. 1).

Because the driving rocker 11 is received within the coupling element16, the motion of the driving rocker 11 is transferred onto the brushhead carrier 17, with the brush head carrier 17 advantageously notrotating about itself either, so that a rubber elastic bearing elementcan be used here as well for the ball-and-socket joint 18. Depending onthe geometric conditions, particularly on the distance l₃ between thejoint 18 and the point of engagement of the coupling element 16 and thedriving rocker 11, a cone angle α₂ (see FIG. 1) results for the likewisedouble-conical orbital motion of the brush head carrier 17. By means ofan offset of the point of attachment of the respective cleaning elementholder 27 on the leg 25 by the angle β (see FIG. 1) relative to thecenterline or longitudinal axis of the brush head carrier 17, thecleaning element 28, which is arranged perpendicular to the brush headcarrier axis, performs a three-dimensional motion relative to a standingtooth in height direction z, in length direction x and in widthdirection y, as can be seen more clearly from FIG. 2.

Through displacement of the sliding member 19 within the brush tube 3,the position of the point of engagement 32 of the driving rocker 11 andthe brush head carrier 17 changes within the coupling element 16, andwith it the amplitude of the transferred motion. Through displacement ofthe sliding member 19, the cone angle α₂ of the orbital motion of thebrush head carrier 17, and therefore the amplitude of the motion of thecleaning fork 23, can be adjusted. The adjusting device formed by virtueof the displaceability of the sliding member 19 allows the cleaningmotion to be adjusted to the preferences of the user.

The amplitude of the cleaning motion may also be adjusted via theeccentricity e of the eccentric member 10. FIG. 3 shows various possibleembodiments of the eccentric member 10, which may be replaceably securedto the motor shaft 9. Eccentric members 10 may also find applicationwhere an infinitely variable adjustment of the pivot point 31 of thedriving rocker 11 is possible.

Furthermore, an adjustment of the amplitude of the cleaning motion mayalso be achieved by means of an adjustment of the length l₄, i.e., thedistance between the cleaning fork 23 and the pivot point 18 of thebrush head carrier 17. For example, the brush head carrier 17 can bepulled out and extended, or the cleaning fork 23 can be fastened in amanner which allows it to be displaced in the longitudinal direction ofthe brush head carrier 17 relative to the latter.

The amplitude of the cleaning motion is defined by the eccentricity e(see FIG. 3) of the eccentric member 10, the lever lengths l₁ to l₄ andthe angle β. Through adjustment of the eccentricity, the lever lengthsl₁ to l₄ and the angle β it is possible to adjust the variables δ_(x),δ_(y) and δ_(z) in relation to the motion axes shown in FIG. 2, e.g.,from 0 mm-10 mm, with an infinitely variable adjustment.

Due to the tension of the legs 25 of the cleaning fork 23 in thedirection of the tooth width y (see FIG. 2), i.e., the resilient bias ofthe legs 25 towards each other, and due to a flexible mounting of thecleaning elements 28 or the cleaning element holders 27 on the legs 25,the cleaning elements 28 can always make full surface contact, on bothsides, with both wide molars and narrow incisors.

FIGS. 2 and 5 show another embodiment of the cleaning fork 23. Incomparison to the embodiment shown in FIG. 1, the cleaning fork isarranged rotated through 90°, so that the entire insides of the legs 25can be directly lined with a piece of plush or velvet 29. The cleaningfork 23 is formed U-shaped in cross-section, with the free ends of thelegs 25 expanding outwardly in a bell-shaped configuration. The cleaningfork 23 is mounted on the brush head carrier 17 in a manner whichpermits rotation about an axis of rotation 33 which is arrangedperpendicular to the longitudinal axis of the brush head carrier 17. Thecorresponding swivel joint 34 is preferably of the retarding typecausing deceleration of the rotary motion of the cleaning fork 23 aboutthe axis of rotation 33. Due to the arrangement of the cleaning fork 23shown in FIG. 5, it can slide from the left-hand side of the jaw to theright-hand side of the jaw while sitting on the teeth, and while thecleaning fork rotates relative to the brush head carrier 17. As shown inFIG. 2, the cleaning fork is lined with plush or velvet also on thebottom of the “U” shape, i.e., also on the cross bar connecting the twolegs 25. As a result, it is possible to achieve efficient, tooth-huggingcleaning, during which the upper sides of the teeth are also cleaned atthe same time.

FIG. 4 shows an embodiment which is slightly modified in comparison toFIG. 1 and differs in terms of the driving rocker 11. Instead of adriving rocker 11, a drive shaft which rotates with an eccentric memberis provided. The motor shaft 9 protrudes from the forward end of thegrip section 1 and extends into the brush tube 3. At its end close tothe brush head carrier 17, the motor shaft 9 includes an eccentricmember 10 which is formed as an elbowed hook, in the embodiment shown.The eccentric member 10 engages in the coupling element 16 provided onthe brush head carrier 17, and drives the brush head carrier 17 again ina double-conical orbital motion via the coupling element 16. In order toprovide a seal between the motor shaft 9 and the grip section housing 4,a radial shaft seal 35 is provided which sits in the correspondingrecess in the forward end wall 12, through which the motor shaft 9extends. In all other aspects, the embodiment of FIG. 4 corresponds tothe embodiment of FIG. 1, as a result of which like reference numeralsare used for like parts and reference is made to the precedingdescription.

In the embodiment of FIGS. 6 to 9, the brush head 2 is not driven by abrush head carrier moving in an orbital path on a double cone, but it isinstead driven in an oscillatory motion. A drive shaft 9 projects fromthe forward end of the grip section 1 of the electric toothbrush. Thedrive shaft 9 performs at least one of the following motions: anoscillatory rotational motion 36 about the longitudinal axis 8 of thetoothbrush or the drive shaft axis which coincides with this; anoscillatory rotational motion 37 about a swivel axis 38 (see FIG. 6),which extends transversely to the longitudinal axis of the toothbrush,and, advantageously, extends in the forward end portion of the gripsection 1, and substantially perpendicular to the plane of symmetry 39of the cleaning fork 23 (see FIG. 9); an oscillatory rotational motion40 about a swivel axis 41, which extends transversely to thelongitudinal axis 8 of the toothbrush and substantially parallel to theplane of symmetry 39 of the cleaning fork 23 (see FIG. 7); and atranslatory oscillation 42 in a direction parallel to the longitudinalaxis 8 of the toothbrush.

The drive shaft 9 seats the brush tube 3, which is secured by means ofcatches, not shown, in a detachable manner.

The front part of the brush tube 3 on the side close to the brush head 2includes a rectangular channel 43 into which two arms 44, which areintegrally molded onto a bearing element 45, are inserted. Each arm 44carries a lug 46, each of which engage in a respective aperture orcutout 47 of the brush tube 3. This enables the bearing element 45 to beinserted from the forward end into the brush tube 3 for attachmentthereto. In the interior of the brush tube 3 are four grooves 48, byvirtue of which in conjunction with the two cutouts 47 two spring arms49 result. The free end of the spring arms 49 rests on a free end 50 ofthe arms 44. When the user exerts pressure on the spring arms 49 in thearea of rounded protuberances 51 (see FIG. 8), the lugs 46 aredisengaged. This enables the bearing element 45 to be pulled out fromthe brush tube 3.

The cleaning fork 23 is rotatably mounted in a bore 52 of the bearingelement 45, and has a bearing journal 53 with an axis 54, two legs 25and a cross bar 55 connecting the two legs 25. The bearing journal 53has two lugs 56 and a slot 57 at its free end, through which the lugs 56are capable of springing back inwardly. For assembly the bearing journal53 is pressed into the bore 52 of the bearing element 45, such that thelugs 56 are pressed together against the spring action. After passingthrough the bore 52, the lugs 56 expand again due to the spring action,so that the bearing journal 53 is rotatable, but sits axially fixed inthe bearing element 45.

The cleaning fork 23 can be infinitely rotatable relative to the bearingelement 45. However, in the embodiment shown, the rotatability ofcleaning fork 23 is limited by a rotation stop 58 (see FIG. 6).

As shown in FIG. 9, the legs 25 enclose an angle γ which is preferablybetween 15° and 45°. At their free end they have a bell-shaped curvedportion 59 which is bent outwardly.

The inside of the legs 25 and the cross bar 55 connecting the legs 25carries a piece of velvet or plush 29, which may be secured by means ofadhesive bonding, hot-sealing or by other methods.

Preferably the piece of velvet or plush 29 comprises a piece of fabric60 and a pile 61, which may both be made of polyamide. In the region ofthe cross bar 55 and the adjoining legs 25 the threads of the pile 61may preferably have a thickness of 3/1000 to 5/1000 of an inch, and atthe bell-shaped curved portion 59 of the legs 25 they preferably have athickness of 2/1000 to 4/1000 of an inch. The thickness of the threadsof the pile 61 may vary within a region.

The depth of the pile 61 may vary. Advantageously, the depth H₁ of thepile 61 in the region of the cross bar 55 is approximately 2 mm to 6 mm,while the depth H₂ of the pile 61 at the legs 25 and their bell-shapedcurved portions 59 may amount to approximately 4 mm to 8 mm. The depthsH₁ and H₂ may also vary within their regions.

In the embodiment shown, the distance 62 between the longitudinal axisof the brush tube 3 and a free area of the pile 61 is preferablyapproximately −6 mm to +6 mm.

FIGS. 10 to 13 clarify the way in which the toothbrush works. Thecleaning fork 23 can be placed with the cleaning elements 28 made ofplush or velvet on a tooth 63 or 64. The elasticity of the legs 25 ofthe cleaning fork 23 and of the pile 61 of the piece of plush or velvet29 compensates for the varying thicknesses of incisors 63, shown in FIG.10, and molars 64, shown in FIG. 11. When the drive shaft 9 performs theoscillatory rotational motion 36 about the longitudinal axis 8, thevestibular, occlusal and lingual dental surfaces are cleanedsimultaneously.

As becomes apparent from FIG. 13, the axis of rotation 33, about whichthe cleaning fork 23 can be rotated relative to the bearing element 45of the brush head carrier 17, enables the toothbrush to be drawn fromthe left-hand side of the jaw 65 to the right-hand side, while thecleaning fork is placed on the teeth. To clean the entire jaw 65, theuser holds the grip section 1 and draws the cleaning fork 23 togetherwith the piece of velvet or plush 29 under continuous oscillatory drivemotion of the brush head slowly across all of the teeth in the jaw 65.By virtue of the rotatability of the cleaning fork 23 about the axis ofrotation 33 all teeth are evenly cleaned.

As shown in FIG. 12, the cleaning fork 23 may be equipped with anadditional weight 66 positioned at a distance from the axis of rotation33, which causes an imbalance of the cleaning fork 23. This enables thecleaning fork 23 to perform an oscillatory rotational motion 67 aboutthe axis of rotation 33 when the oscillatory rotational motion 36 actsabout the longitudinal axis 8 of the toothbrush.

FIGS. 14 to 18 show a variant of the toothbrush from the precedingFigures. The end portion of the brush tube 3 on the side close to thebrush head 2 contains an oval channel 43 with two slots 68, into whichtwo arms 44, which are integrally molded onto the bearing element 45 ofthe brush head carrier 17, are inserted. A free end 50 of the arms 44lies in the interior of the channel 43, each arm 44 carrying a lug 46,each of which engage within a respective aperture or cutout 47 of thebrush tube 3. This arrangement secures the bearing element 45 in thebrush tube 3. When the user exerts pressure on the arms 44 in the areaof rounded protuberances 51 then the lugs 46 are disengaged, enablingthe bearing element 45 of the brush head carrier 17 to be pulled outfrom the brush tube 3.

A cleaning fork 23 constructed as a double fork is mounted in a bore 52of the bearing element 45. The cleaning fork 23 has a bearing journal 53with an axis 54, four legs 25 which stand in pairs facing in opposingdirections and a respective cross bar 55 which connects each of thepairs of legs 25. The assembly with the bearing element 45 and thecleaning fork 23 may be manufactured using the two-component injectionmolding method in which first the bearing element 45 is injection moldedfrom plastic and then the cleaning fork 23, which is formed as a doublefork and is made of plastic, is injection molded onto the bearingelement 45. In the process, the bearing journal 53 of the cleaning fork23 shrinks to an extent producing a radial clearance sufficient toprovide rotatability of the cleaning fork 23 about the axis of rotation33. In order to produce the axial clearance the injection mold may havea tongue in a gap 69 between the bearing element 45 and one of the crossbars 55.

It will be understood that it would also be possible to manufacture thecleaning fork 23 which is formed as a double fork and the bearingelement 45 by other means. For example, the bearing element 45 and/orthe cleaning fork 23 may be formed as a two-part structure.

The insides of the forks formed by the legs 25 and the cross bars 55 areeach fitted with a piece of velvet or plush 29 in the manner describedin the foregoing.

The embodiment of FIGS. 14 to 16 allows the teeth on the upper jaw andlower jaw to be cleaned simultaneously.

In the embodiment of FIG. 19, a latch 70 having a collar 71 is mountedin the channel 43 of the brush tube 3 for displacement parallel to thelongitudinal axis 8 of the toothbrush. The latch 70 is urged by a spring72 against the end of the drive shaft 9. With the brush tube 3 seated onthe drive shaft 9, the forward end of the latch 70 lies between the freeends 50 of the arms 44, as a result of which the bearing element 45cannot be separated from the brush tube 3. In this way, accidentalrelease of the bearing element 45 by the user is prevented. If the brushtube 3 is taken off the drive shaft 9, then the spring 72 slides thelatch 70 rearward, as a result of which the free ends 50 of the arms 44are released. Now the bearing element 45 can be pulled off from thebrush tube 3 by virtue of the user exerting pressure on the roundedprotuberances 51.

In the embodiment of FIG. 20 the arms 44 of the bearing element 45 areso long that their free ends 50 lie to both sides of the forward end ofthe drive shaft 9 when the brush tube 3 is pushed onto the drive shaft9. In this state the bearing element 45 cannot be separated from thebrush tube 3, similarly to the embodiment of FIG. 14. When, by contrast,the brush tube 3 is taken off from the drive shaft 9, then the free ends50 of the arms 44 are released, as a result of which the bearing element45 can be pulled off from the brush tube 3 by virtue of the userexerting pressure on the rounded protuberances 51.

Advantageously, by suitably dimensioning the cleaning fork 23, inparticular its legs 25 and cross bar 55, a natural bending frequency ofthe legs 25 that is identical to the frequency of the oscillatoryrotational motion 36 about the longitudinal axis 8 of the toothbrush canbe achieved. As a result, the legs 25 perform a bending oscillation 73(see FIGS. 9 and 18), which enhances the cleaning action.

It will be appreciated that the cross-section of the channel 43 at theforward end of the brush tube 3 does not necessarily have to berectangular or oval; other cross-sectional shapes are also possible.

In some embodiments, the piece of plush or velvet 29 may provide a depotfor chemical and/or biological agents. The active agents may be enclosedin micro-capsules which break open on use. The threads of the piece offabric 60 and/or the pile 61 may be made of synthetic material which isdoped with silver, or a small proportion of the synthetic material canbe made of silver in order to achieve an antibacterial effect.

The pieces of plush or velvet 29 may be secured in different ways andmeans to the cleaning fork 23. According to one embodiment, therespective piece of plush or velvet 29 may be severed from a length ofplush or velvet material by means of a hot stamp or a laser beam. Inboth methods the heat fuses the cut threads together, which preventsfraying. The fabric of the velvet or plush may also be impregnated witha suitable medium, and then cold-stamped or cut out, e.g., with the aidof a water jet. Here, the impregnating prevents fraying.

The respective piece of velvet or plush 29 may be adhesively bonded orwelded onto the inside of the legs 25 of the cleaning fork 23. Byproviding contact across the entire surface it is ensured that therespective piece of velvet or plush 29 exactly corresponds to thepredetermined contour of the leg 25 of the cleaning fork 23.

FIG. 21 shows by contrast an embodiment in which the piece of velvet orplush 29 is only affixed in points or lines to the insides of thecleaning fork 23 or its legs 25. As is shown in particular in FIG. 21A,a piece of velvet or plush may be secured on the one hand to the freeends of the legs 25 and on the other hand to the base of the cross bar55 connecting the legs 25. When the cleaning fork 23 is positioned on atooth for cleaning, then the piece of velvet or plush 29 restselastically against the contour of the tooth, as shown in FIG. 21B.

FIGS. 22 A-B shows a method suitable for manufacturing a cleaning fork23. To start with, a piece of velvet or plush 29 is connected to acleaning fork blank, which is still planar, for example by means ofadhesive bonding or welding. The cleaning fork blank, which is stillplanar and has the piece of velvet or plush attached to it, is thenplaced on a die 74 having a cavity 75 which corresponds to the desiredcontour of the cleaning fork and into which the cleaning fork blank isthen drawn by vacuum application through a vacuum duct 76. For thispurpose the cleaning fork blank may be suitably heated as required.

FIG. 23 A-B shows an alternative way of securing the piece of velvet orplush 29 to the respective leg 25 of the cleaning fork 23 or the stillunformed blank therefor. Positive engagement is achieved by sliding thepiece of velvet or plush 29 onto a mandrel 77, so that the mandrelpenetrates through the material of the piece of plush or velvet. Bymeans of a tappet 78 the mandrel 77 is then shaped to form a mushroom-or rivet-like head which holds the piece of plush or velvet 29 in placeon the mandrel and preferably clamps it securely.

1. An electric toothbrush comprising: a grip sections; a brush head,mounted on the grip section for movement relative thereto and a drivemechanism operable to drive the brush head in one or more of anoscillatory and an orbital motion; wherein the brush head comprises acleaning element with a piece of plush or velvet on an outer surfacethereof and exposed to contact tooth surfaces.
 2. The toothbrushaccording to claim 1, wherein the piece of velvet or plush comprises apiece of fabric and a pile extending from the fabric.
 3. The toothbrushaccording to claim 2, wherein the pile has a depth of between 2 and 8mm.
 4. The toothbrush according to claim 2, wherein the piece of plushor velvet has pile yarn of a thickness between 0.05 and 0.2 mm.
 5. Thetoothbrush according to claim 31, wherein the plush or velvet has a pilethat is deeper at free ends of the legs than at a root section of thelegs.
 6. The toothbrush according to claim 31, further comprising across bar, connecting the legs of the cleaning fork and provided with apiece of plush or velvet on a surface thereof.
 7. The toothbrushaccording to claim 31, wherein the legs of the cleaning fork are sprung.8. The toothbrush according to claim 31, wherein the legs of thecleaning fork enclose an angle of between 15 and 45 between each other.9. The toothbrush according to claim 1 further comprising a brush headcarrier, on which the brush head is mounted for rotation about atransverse axis which extends substantially perpendicular to alongitudinal axis of the toothbrush.
 10. The toothbrush according toclaim 31, wherein the cleaning fork has an axis of symmetry extendingsubstantially in a direction transverse to a longitudinal axis of thetoothbrush.
 11. The toothbrush according to claim 1, wherein the drivemechanism has a drive axis which is parallel to a longitudinal axis ofthe toothbrush and about which the brush head is adapted to be driven.12. The toothbrush according to claim 11 wherein the drive mechanismcomprises a motor and a brush head carrier upon which the brush head isseated and wherein the drive mechanism includes a driving rocker mountedat a pivot point between the brush head and the motor.
 13. Thetoothbrush according to claim 1, wherein the drive mechanism includes anadjusting device operable to adjust a stroke of the motion of the brushhead.
 14. The toothbrush according to claim 13, wherein the drivemechanism comprises a brush head carrier constructed as a driving rockerpivotable at a pivot point of the brush head carrier that isdisplaceable in a longitudinal direction of the toothbrush.
 15. Thetoothbrush according to claim 12, wherein the brush head carrier isnon-rotationally mounted about its longitudinal axis, and is fastened toan elastic bearing element at the pivot point.
 16. The toothbrushaccording to claim 12 wherein the driving rocker is adapted to be drivenin a spatially orbital motion.
 17. The toothbrush according to claim 16further comprising an elastic bearing element, wherein the drivingrocker is non-rotationally mounted about its longitudinal axis and isfastened to the elastic bearing element at the pivot point.
 18. Thetoothbrush according to claim 12, wherein the driving rocker is coupledto the brush head carrier with substantially zero play in a directiontransverse to the longitudinal axis of the toothbrush.
 19. Thetoothbrush according to claim 12 wherein the driving rocker and iscoupled to the brush head carrier in a manner that provides for play ofthe driving rocker relative to brush head carrier in at least onedirection transverse to the longitudinal direction of the toothbrush.20. The toothbrush according to claim 1 wherein the drive mechanismincludes a drive shaft having an eccentrically rotating drive memberoperable to drive the head.
 21. The toothbrush according to claim 1,wherein the drive mechanism has a drive axis which is parallel to alongitudinal axis of the toothbrush and about which the brush head isadapted to be driven in an oscillatory rotational motion.
 22. Thetoothbrush according to claim 1, wherein the drive mechanism has a driveaxis which is parallel to a longitudinal axis of the toothbrush andalong which the brush head is adapted to be driven in a translatoryoscillating motion.
 23. The toothbrush according to claim 1, wherein thedrive mechanism has a drive axis which extend in a direction transverseto a longitudinal axis of the toothbrush and about which the brush headis adapted to be driven in an oscillatory rotational motion.
 24. Thetoothbrush according to claim 23, wherein the drive axis extendsparallel to a plane of symmetry of the cleaning element and is spacedfrom the brush head on a grip section side of the brush head.
 25. Thetoothbrush according to claim 23, wherein the drive axis extendsperpendicular to a plane of symmetry of the cleaning element and isspaced from the brush head on a grip section side of the brush head. 26.The toothbrush according to claim 31, wherein the cleaning fork includeslegs extending in pairs towards opposing directions.
 27. The toothbrushaccording to claim 1, wherein the piece of velvet or plush is fastenedto the cleaning element by adhesive bonding or by hot-sealing.
 28. Thetoothbrush according to claim 27, wherein the piece of velvet or plushis adhesively bonded to the cleaning element by a silicone adhesive. 29.The toothbrush according to claim 1, wherein the brush head isdetachable from the grip section.
 30. The toothbrush according to claim1 further comprising a brush tube, wherein the brush head is mounted onthe brush tube which is releasably secured to the grip section of thetoothbrush.
 31. The toothbrush according to claim 1, wherein thecleaning element comprises a cleaning fork having legs with insidesurfaces on which the piece of plush or velvet is disposed.
 32. Thetoothbrush according to claim 31, wherein the plush or velvet is thinnerat free end ends of the legs of the cleaning fork than at a root sectionof the legs.
 33. The toothbrush according to claim 31, wherein the legsof the cleaning fork have bell-shaped expanded portions at their freeends.
 34. The toothbrush according to claim 9, wherein the brush head isrotatable without being driven by forces applied to the cleaningelement, without being driven by the drive mechanism.
 35. The toothbrushaccording to claim 12, wherein the drive mechanism includes a partitionbetween the brush head carrier and the drive rocker.
 36. The toothbrushaccording to claim 3, wherein the pile has a depth of between 3 and 6mm.
 37. The toothbrush according to claim 2, wherein the fabric and pileboth comprise polyamide.